BAP1 tumor predisposition syndrome

BAP1 tumor predisposition syndrome is an inherited disorder that increases the risk of a variety of cancerous (malignant) and noncancerous (benign) tumors, most commonly certain types of tumors that occur in the skin, eyes, kidneys, and the tissue that lines the chest, abdomen, and the outer surface of the internal organs (the mesothelium). Affected individuals can develop one or more types of tumor, and affected members of the same family can have different types.

Some people with BAP1 tumor predisposition syndrome develop growths in the skin known as atypical Spitz tumors. People with this syndrome may have more than one of these tumors, and they can have dozens. Atypical Spitz tumors are generally considered benign, although it is unclear if they can become cancerous. Skin cancers are also associated with BAP1 tumor predisposition syndrome, including cutaneous melanoma and basal cell carcinoma.

A type of eye cancer called uveal melanoma is the most common cancerous tumor in BAP1 tumor predisposition syndrome. Although uveal melanoma does not usually cause any symptoms, some people with this type of cancer have blurred vision; small, moving dots (floaters) or flashes of light in their vision; headaches; or a visible dark spot on the eye.

People with BAP1 tumor predisposition syndrome are at risk of developing malignant mesothelioma, which is cancer of the mesothelium. When associated with BAP1 tumor predisposition syndrome, malignant mesothelioma most often occurs in the membrane that lines the abdomen and covers the abdominal organs (the peritoneum). It less commonly occurs in the outer covering of the lungs (the pleura).

A form of kidney cancer called clear cell renal cell carcinoma is also associated with the condition. Researchers are still determining whether other forms of cancer are linked to BAP1 tumor predisposition syndrome.

When they occur in people with BAP1 tumor predisposition syndrome, cancers tend to arise at a younger age and are often more aggressive than cancers in the general population. The cancerous tumors in BAP1 tumor predisposition syndrome tend to spread (metastasize) to other parts of the body. Survival of affected individuals with this syndrome is usually shorter than in other people who have one of these cancers. However, individuals with malignant mesothelioma as part of the BAP1 tumor predisposition syndrome appear to survive longer than those who have the cancer without the syndrome.

BAP1 tumor predisposition syndrome is inherited in an autosomal dominant pattern, which means one copy of the altered BAP1 gene increases the chance of developing one or more tumors. In most cases, an affected person has one parent with the condition. Over 70 mutations, all rare, are known; the most frequent is likely to be rs387906848.[PMID 28793149]